1. Field of the Invention
This invention relates generally to firearms and, more particularly, to a muzzle loading firearm with an improved ignition system.
2. State of the Prior Art
Hunting with muzzle loading firearms has become increasingly popular in the last few years. Many hunters prefer to use muzzle loading rifles because a game animal has a greater chance to escape with its life, and, thus, the hunter's skill can be more adequately tested. Some hunters also enjoy the muzzle loading routine of pouring powder down the rifle barrel, packing it, and driving a shot down the barrel. Some states even have a separate hunting season for sportsmen with muzzle loading firearms.
Hunting with muzzle loading rifles presents several additional challenges. Most muzzle loading weapons used by hunters fire by means of a cup-shaped percussion cap which contains a small explosive charge ignitable upon application of a sufficient impact. The percussion cap is placed over a nipple. A passageway through the nipple and into the barrel of the weapon passes the hot gasses produced when the percussion cap is ignited. Typically, the muzzle loading hunting season occurs at a time of the year when the weather is cold and inclement. Percussion caps are well known for being an unreliable ignition source in such weather. They absorb moisture and may become waterlogged and unusable. Also, they contain only a small charge. A further inconvenience of percussion caps becomes apparent when a hunter attempts to remove a spent cap from the nipple in the field. Sometimes the cap is very difficult to pry off of the nipple, especially with cold fingers.
To overcome the inadequacies of percussion caps as an ignition source, some gun designers employ shotgun shell primers as an ignition source. Shotgun shell primers are primarily used as the ignition source for shotgun shells for regular breech loading shotguns, but make an excellent ignition source for a muzzle loading weapon. They comprise a tubular metal casing, an annular flange at one end of the casing and extending outwardly radially therefrom, a charge of explosive material, and a hole at the opposite end from the flange for expelling the hot gasses from the explosion.
Shotgun shell primers are much less susceptible to the ravages of damp weather and rarely become waterlogged unless immersed in water. Shotgun shell primers also contain a much larger charge of explosive material for a more reliable ignition of the black powder charge. However, previous ignition systems for muzzle loading weapons designed to use shotgun shell primers as an ignition source require that the primer be inserted into a tight fitting well until the annular flange prevents the primer from being inserted further. The primer must fit snugly into the well to prevent it from falling out. Many times gasses and ash blowing back into the ignition system from the exploding black powder charge dirty the well. When this happens, the primer is very difficult to insert and remove. Even when the well is relatively clean, the primer is difficult to remove with cold hands.
A second problem with muzzle loading weapons is accuracy. One element of inaccuracy is a relatively long lock time compared with conventional breech-loading weapons. Lock time is measured from the time the trigger is squeezed until the black powder charge launching the bullet actually fires. Many muzzle loading weapons employ a traditional swing hammer mounted on the side of the barrel, which swings through an arc and strikes a percussion cap. The hot gasses from the cap must travel a long, and sometimes circuitous, path into the barrel before igniting the black powder charge. Also, if only the side of the charge is ignited it may not burn evenly. The longer the lock time, the longer the shooter has to hold the rifle steady and on target. Even very small delays can cause inaccuracies due to the physical inability of even the best shooters to hold the weapon completely still. Small movements of the rifle greatly affect the bullet's path.
To reduce lock time, it is desireable to have a fast hammer and a short direct path from the ignition source into the black powder charge. Recently, in-line firing systems have gained some popularity for their inherently faster lock times, thus higher accuracies. The firing mechanism and ignition source are lined up immediately behind the black powder charge to reduce the distance the hammer has to travel and also the distance that the hot gasses have to travel. The gasses enter the barrel axially to reduce uneven burning of the black powder charge. If used with a shotgun shell primer, lock time may be further reduced by providing a hotter spark to more quickly ignite the black powder charge.
A drawback of such systems is the awkward placement of the percussion cap nipple or primer well inside the barrel. Typically they are accessed through an opening in the side of the barrel. Access is difficult because of the small space for putting one's fingers. In cold weather, access is even more difficult due to the limited mobility of cold fingers.